1. Field of the Invention
This invention is directed to biocidal compositions containing a haloalkynyl compound, and especially a halopropargyl compound. The invention is particularly directed to such compositions containing such compounds which have been stabilized to reduce the loss of biocidal activity due to the degradation of such compounds. The invention is especially directed to the stabilization of compositions containing iodopropargyl carbamates, such as 3-iodo-2-propargylbutyl carbamate.
2. Description of the Related Art
Both exterior and interior surfaces and substrates of all types, when exposed to common environmental conditions, e.g. moisture, are prone to attack, discoloration and various kinds of destruction by a variety of species of microorganisms, including fungi, algae, bacteria and protozoa. As a result, there is a great need and requirement for an effective and economical means to protect for extended periods of time both exterior and interior surfaces and various type substrates and commercial formulations from the deterioration and destruction caused by such microorganisms.
Materials which need protection with a suitable antimicrobial composition include stucco, concrete, stone, cementaceous surfaces, wood, caulking, sealants, leather, plastics, textiles, biodegradable compositions including such materials as paints and other coating formulations, surfactants, proteins, starch-based compositions, inks, emulsions and resins as well as numerous other materials and other substances which may be attacked by destructive microbes.
An enormously wide variety of materials have been identified which, to various degrees, are effective is retarding or preventing the growth of, and accompanying destruction caused by, such microbes. Such biocidal compounds include halogenated compounds, organometallic compounds, quaternary ammonium compounds, phenolics, metallic salts, heterocyclic amines, formaldehyde donors, organo-sulfur compounds and the like.
Formulated products that are protected against microbial attack by the inclusion of such biocidal additives must retain their biocidal activity for a prolonged time period to be most useful. Indeed, such products often are used to impart a biocidal activity to another product or to a substrate, such as wood and the like, which itself requires extended protection against microbial attack.
One well-known class of biocides are those containing a halopropargyl moiety, and especially an iodopropargyl moiety. Such compounds are widely disclosed in the patent literature including U.S. Pat. Nos. 3,660,499; 3,923,870; 4,259,350; 4,592,773; 4,616,004 and 4,639,460 to name a few. Included within this class of compounds are the halopropargyl carbamates which are known primarily for their fungicidal activity. 3-iodo-2-propargyl butyl carbamate, hereinafter also referred to as IPBC, is one of the best known and probably the most widely used of the halopropargyl carbamate fungicides. IPBC is a highly active broad spectrum fungicide. In addition to its fungicidal activity, IPBC also has been associated with algaecidal activity. In this regard, Great Britain Patent 2,138,292 and U.S. Pat. Nos. 4,915,909 and 5,082,722 contain such disclosures.
As noted above, the haloalkynyl compounds, including halopropargyl compounds, and especially the halopropargyl carbamates typically are formulated with a variety of other ingredients, in both aqueous and organic solvent mixtures. For various reasons, it is desired that these compositions maintain their biocidal activity for prolonged periods of time. Unfortunately, such compositions have sometimes been observed to experience a progressive loss in such activity. Until now, the reason for such degradation has not been understood. Through experimentation, however, applicants have found that one prevalent cause for the loss of biocidal activity in such formulations is exposure of the haloalkynyl compound to high levels of alkalinity or high levels of acidity. In an aqueous environment, such conditions involve an extreme pH condition, both acidic and basic. Applicants have discovered that by formulating the composition so as to neutralize the acid or alkaline source in the composition, or by buffering the formulation, degradation of the biocidal haloalkynyl compound, including specifically halopropargyl compounds such as IPBC, can be significantly retarded. The invention also helps to ameliorate other problems, such as the formation of lacrimators or corrosion of metal containers, caused by the degradation of IPBC in solvent-based alkyd paint formulations.